Analyses of amino acid sequences in hypervariable region-1 of hepatitis C virus (HCV) in sera from chimpanzees infected three times with the same HCV strain

Background  To investigate whether or not the same strain of hepatitis C virus (HCV) can twice re-infect the same chimpanzee, we analyzed nucleic and amino acid sequences in HCV hypervariable region-1 (HVR1). Two chimpanzees were inoculated, three times each, with the same HCV strain during the 1983–1991. After each inoculation, chimpanzees developed acute hepatitis C, and then recovered.
Methods  Using sera, HVR1 cloning and antibody to HVR1 major clone measurement were performed.
Results  Clones from the first inoculum were divisible into major and minor types. Clones from the second and third inocula, as well as all post-inoculation sera, were essentially identical to the major type. Titers of antibody to HVR1 major clone were consistently low in pre- and post-inoculation sera.
Conclusions  Both chimpanzees were re-infected twice with the same strain of HCV. The sequences from the second and third infections were similar to the major sequences in the first inoculum.     

特异性IgG抗体在异种/同种异株疟原虫感染治愈后P.y17XL再感染中的保护作用

为探讨特异性IgG抗体在异种/同种异株疟原虫治愈后再感染过程中的作用,用不同种/株疟原虫感染BALB/c小鼠,经治愈后用P.y17XL再感染。通过计数红细胞感染率和检测再感染后血清中特异性IgG抗体的水平变化,发现P.y17XNL感染治愈组小鼠几乎不出现原虫血症,其余异种疟原虫感染治愈组小鼠出现了不同程度的虫血症发生时相延迟和水平降低,部分生存率有所延长;不同虫种/株感染治愈后P.y17XL再感染的小鼠IFN-γ水平均明显低于同时间点P.y17XL初次感染的小鼠;P.v、P.y17XNL感染治愈小鼠血清中P.y17XL特异性IgG抗体水平出现显著增加(P<0.05),且以IgG1亚类升高为主。表明特异性IgG抗体可在宿主抗同源疟原虫再感染中发挥着重要作用,而对异种疟原虫再感染保护性有限。